(a) Prohibited Uses. Evidence of the following is not admissible — on behalf of any party — either to prove or disprove the validity or amount of a disputed claim or to impeach by a prior inconsistent statement or a contradiction:

(1) furnishing, promising, or offering — or accepting, promising to accept, or offering to accept — a valuable consideration in compromising or attempting to compromise the claim; and

(2) conduct or a statement made during compromise negotiations about the claim — except when offered in a criminal case and when the negotiations related to a claim by a public office in the exercise of its regulatory, investigative, or enforcement authority.

(b) Exceptions. The court may admit this evidence for another purpose, such as proving a witness’s bias or prejudice, negating a contention of undue delay, or proving an effort to obstruct a criminal investigation or prosecution.

In Main, the plaintiffs were convicted sex offenders who have completed prison sentences but remain involuntarily confined pursuant to the New Jersey Sexually Violent Predator Act ("NJSVPA"), which authorizes the indefinite civil commitment of any individual determined to be a "sexually violent predator." The plaintiffs claimed, inter alia, that the various defendants failed to provide them with adequate mental health treatment required by federal and state law.

In 2008, after the parties had reached an impasse over what would constitute adequate mental health treatment at the [New Jersey's Special Treatment Unit (STU)], the parties agreed upon the utilization of a joint neutral expert, Judith Becker, Ph.D., who was selected by Plaintiffs' pro bono counsel and Defendants....The concept was that Dr. Becker would review the existing STU treatment program, offer her opinion on the program, and produce a report, which would be considered solely for purposes of breaking the stalemate in settlement discussions. On December 29, 2008, Dr. Becker issued her report.

The parties thereafter reached a settlement and filed a joint motion for final approvement of that settlement. Other objectors, however, asked that the settlement not be approved so that the case could proceed to trial. Specifically, according to the court,

some objectors still seem to think that liability can be easily established in light of the Becker Report, which they contend is the report of the State's "own expert." This oversimplifies the liability issue in the case and ignores that the Becker Report does not utilize the Youngberg standard, wholly apart from the fact that there are serious issues regarding whether the Becker Report would even be admissible at a trial.[FN31]

FN31. There is some disagreement among the parties as to whether Dr. Becker's report was to be considered for settlement purposes only pursuant to Federal Rule of Evidence 408. The relevant procedural history suggests that the Becker Report was for settlement purposes only and would not be properly admissible at trial.